Recently, with the rapid progress in the information industry, various information processing systems have been developed, and a recording method and apparatus suitable for the various information processing systems have been developed and practically employed.
One such information recording method is a heat transfer recording method, and the apparatus used for the recording method has the advantages of being light-weight, compact and noiseless. Further, the apparatus is excellent in operability and maintenance, and color images can be easily recorded. The heat transfer recording method has recently been widely used.
The heat transfer recording method is generally classified into a heat melting type recording method and a heat shifting recording method.
In the latter method, a heat transfer dye-providing material having a dye-providing layer containing a binder and a heat shifting dye on a support is superposed on a heat transfer image-receiving material, and heat is applied in a pattern to the assembly from the support side of the dye-providing material. The heat shifting dye is transferred and heated in a pattern onto the recording medium (the heat transfer image-receiving material) to form transferred images.
In addition, the heat shifting dye used in the heat shifting method is a dye which can be transferred from a heat transfer dye-providing material to a heat transfer image-receiving material by sublimation or diffusion in a medium.
However, the heat transfer dye-providing material used for the heat shifting type heat transfer recording method has the following problem. For forming multicolor images, usually transfers three successive times using heat transfer sheets of 3 color, i.e., yellow, magenta, and cyan, is required, for one multicolor image. Three dye transfer sheets having a yellow dye transfer portion, a magenta dye transfer portion, and a cyan dye transfer portion, respectively are prepared. Each dye transfer sheet is superposed on one image-receiving sheet followed by heating by a thermal head. The above procedure is carried out three times to form a multicolor image.
In this case, a problem occurs in that contact between the dye-providing sheet and the image-receiving sheet is insufficient so when they are moved in the superposed state for heating, these sheets are shifted from each other. It has been found that this is caused by a deficiency in friction between the surface of the dye-containing layer of the dye-providing sheet and the image-receiving surface of the image-receiving sheet in contact with each other. Hence the aforesaid problem can be solved by increasing the friction force between both sheets.
Thus, various investigations were made on various additives etc., and surface forms of the sheets for increasing the friction force, but it was difficult to obtain the necessary friction force without deteriorating the transferring property or forming undesirable influences on color images, and yet avoid side effects such as welding of the sheets, etc.